Problem with Bosch GTS 10

[Dean Jordan]

Hi all, I am new to this forum, but looking for some advice on my saw

I was using it the other day the some very light tasks. The motor slowed down, the pitch changed to sound quite strange and it massively slowed down and started to smell.
I turned it off. The blade still spun by hand, so nothing was physically restricting it. I took the motor apart and noticed these score marks on the armature. Do you think just replacing this part will solve it, or is there more to my problem?

Thanks in advance for any help/advice anyone has.
Kind regards
Dean.

 

[Old.bodger]

I don’t think those are your problem. If they were damage caused during use they would be on every section of the rotor. I suspect they are where the manufactures have removed material to balance the item. There is little evidence of burning on the commutator but first thing to check is the state and free movement of the carbon brushes. I recently had a drill fail because high resistance in the brush wiring caused heat, heat melted the plastic case mountings, brushes failed to make good contact. After that checks for failed wiring in the body of the saw and then check continuity of each of the windings. Further assistance available !

 

[Spectric]

I would suspect they are machined and maybe have something to do with balance as @Old.bodger has said. To remove that amount of metal and without any marks on the neighbouring laminations does not seem feasable. You need to clean up the commutator and ensure the gaps between the segments are good and take a closer look at the brushes.

 

[Dean Jordan]

I don’t think those are your problem. If they were damage caused during use they would be on every section of the rotor. I suspect they are where the manufactures have removed material to balance the item. There is little evidence of burning on the commutator but first thing to check is the state and free movement of the carbon brushes. I recently had a drill fail because high resistance in the brush wiring caused heat, heat melted the plastic case mountings, brushes failed to make good contact. After that checks for failed wiring in the body of the saw and then check continuity of each of the windings. Further assistance available !

Hi
Thank you for your reply. I am pleased to hear that, as that seems to be the most expensive single part within the saw.

I have removed the plastic caps and the brushes. Although I do not know exactly what I am for, they did seem to have some life left in the carbon, and they did move in their slots freely.
I will have a more indepth look at the wiring.

I would love to take you up on your offer of further assistance. How do I check the continuity of the windings?
Thanks again for your help, I really appriciate it

Dean

 

[Old.bodger]

This is a good place to start.

 

[Old.bodger]

This is a good place to start.

I would be tempted to put it all back together and test again before getting too technical. I suspect that you had a stuck brush and you may have cleared the issue.

 

[Dean Jordan]

Thanks again for the responses.
I will clean the commutator tomorrow, rebuild it and see how it runs. I will video it and feed back.
Failing that, I will follow that youtube clip. I have a multimeter, that doesn`t look too difficult to be honest.

Thanks.
Dean

 

[Dean Jordan]

Hey all

Cleaned it up and put it all back together.

It did run better, and after a bit of a delay got up to full speed, but what I did notice was how much the left hand brush sparked.
What are your thoughts?

 

[Dean Jordan]

It did smell a bit as well

 

[Old.bodger]

I think a new set of brushes. Not usually expensive.

 

[Dean Jordan]

Okay. Ordered a new set, was only £6.
Will let you know how it goes.

Thanks for the help
Dean

 

[Dean Jordan]

Hey all. Happy new year.

Tried the brushes today and no joy. I ran it for a bit longer and it actually stopped dead after a few seconds of smoking before I could turn it off.
I followed the smoke and smell, and it appears to have come from the coil around the magnets. The burn marks and little melted cable ties in the area seem to match up to the smell.

 

[jules_herk.]

Hello,

I’ll follow on this post, since the same kind of problem happened to me.
My GTS10 is from 2015 and has seen some really heavy usage.

Symptoms:
=> motor “stuck” noise, blade trying to spin but can’t start.
=> nasty burnt plastic smell
=> the blade wasn’t breaking properly anymore (that the one I should have concentrated on).

I checked the continuity of the windings (rotor and stator) and the circuit: everything seemed fine.
Which initially made me blame the speed control.
…Bought and put a new on in… A bit better, but inconsistent speed, barely able to start spinning and still burnt plastic smell. The original zip lock holding the windings were melted on the armature, and I had replaced them.
After reading this post I opted not to push it to avoid burning anything else.

I had a closer look at the stator windings: the smell was definitely coming from them.
After having a bit of a back and forth considering the value of the machine in its current state (it’s battered and bruised) and the price of a new stator/armature, I decided to bite the bullet and bought a new one.
The replacement solved the problem.

Note: the replacement armature/stator comes with all cables pre-soldered and attached to the windings, so it’s really an easy drop in replacement. The continental (france) bosch service was really fast and efficient (ordered a tuesday afternoon=> in my mail box by thursday…).

Attached pictures of the autopsy of the old winding.
The nasty plastic smell is definitely the enamel coating of the copper wires.
This also explains the explains the “brake” / slowing of the blade not working properly.

To be honest, I cannot blame it to have failed.
I pushed a lot of tree trunks on this saw, full ones, hard wood, nearly daily.
It’s a really good workhorse, with no real equivalent in this market segment.
Hope this can be helpful to someone else.

Cheerio.